一道Java的题，请高手解答

//抽象类AbstractTest
package help;

public abstract class AbstractTest {
abstract void dispTest();

}

//子类：StudentTest
package help;

public class StudentTest {

private String name;
private int num;
private int score;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getNum() {
return num;
}

public void setNum(int num) {
this.num = num;
}

public int getScore() {
return score;
}

public void setScore(int score) {
this.score = score;
}

public StudentTest() {
}

public StudentTest(String name, int num, int score) {
this.name = name;
this.num = num;
this.score = score;
}

public void dispTest() {

StudentTest st = new StudentTest(name, num, score);
String name = st.getName();
int num = st.getNum();
int score = st.getScore();
System.out.println("姓名:" + name + "\n" + "学号:" + num + "\n" + "分数:"+ score);

}

public static void main(String[] args) {
StudentTest st = new StudentTest("科比", 24, 81);
st.dispTest();
}

}

public abstract class AbstractTest {
public abstract void dispMessage();
}

public class StudentTest extends AbstractTest {

public String name;

public String id;

public Integer score;

public StudentTest(){

}

public StudentTest(String name,String id,Integer score){
this.name=name;
this.id=id;
this.score=score;
}

public void dispMessage() {

}

}

public abstract class AbstractTest {
abstract void dispMessage();
}

public abstract class AbstractTest {
abstract void dispMessage();
}